Rail flaw detector mechanism



Aug.29,1939 H. c. DRAKIIIE 2,170,965

RAIL FLAW DETECTOR MECHANISM Filed July :50, 19:57

T0 AMPLIFIER INVENTOR Patented Aug. 29,1939

RAIL FLAW DETECTOR MECHANISM' Harcourt 0. Brake, Hempstead, N. Y., assignor to Sperry Products. Inc., Brooklyn, N. Y., a corporation of New York Application July so, 1937, Serial No. 156,461 7 10 Claims. (01. 175-183) This invention relates to rail fiaw detector mechanism of the type wherein current is' passed through the rail by a car moving along the rails and an electromagnetic field is thus established 5 surrounding-the rail. Imperfections in the rail cause displacement and distortion .of the said fleld which is otherwise uniform, and such irregularitiesin said field may be detected by any suitable flux responsive means such as the pairs of op- 10 posed induction coils shown in my Patent No.

1,960,968 granted May 29, 1934; or, such variations may be detected by a modified induction coil arrangement as shown in the patent to A. E. F. Billstein No. 1,963,931 granted June 19, 1934 which utilizes the principle that if a conductor is placed in a magnetic field and one end of the conductor is maintained at a different temperature from the other end, then an E. M. F. will be induced in the conductor, which is a function of i the magnetic flux.

This invention is designed to remedy a deficiency in a testing system such as shown in the said Patent No. 1,963,931 wherein-there is employed a vertical bank of coils-which occupies a single relationship with respect to the railhead. In such an arrangement, certain internal defects will cause the electromagnetic field to be distorted in such manner as to increase the flux aflecting said detector coils in one part of said "coils while decreasing the fiux aflecting said coils in other parts thereof, so that the total flux affecting said coils remains unchanged from what it is when no defect is present. Such a condition could be remedied by employing a staggered relation of coils such as shown in my Patent 1,960,968, but this would necessitate the utilization of a plurality of heating units and cooling units, which would make a complicated and expensive arrangement. It is the principal object of this invention, therefore, to provide a rail fiaw detector mechanism of the type disclosed in said Patent No, 1,963,931 which may nevertheless partake of the advantages of a staggered coil arrangement a such as shown in Patent No. 1,960,968 without necessitating the employment of a plurality of heating and cooling units.

Further objects and advantages of this invention will become apparent in the following delo tailed description.

In the accompanying drawing:

. Fig. 1 is a side elevation of a portion of a rail flaw detector car having my invention embodied therein.

Fig. 2 is a diagrammaticview illustrating the method of flaw detection to which my invention pplies. I

Fig. 3 is a. combined vertical section through a. rail and diagram illustrating the theory which necessitates my invention.

Fig. 4 is a plan view andvFlg. 5 is a front elevation of an arrangement of fiux responsivemeans accordingto my invention.

Referring to Fig. 1 of the drawing, a rail fissure g detector car, only a portion lot which is shown,

is mounted on wheels II and carries therein a generator G for supplying current to front and rear sets of brushes l3 and II supported on a current brush carriage adapted to ride upon the rails on eans such as wheels IS. The said car- 16 riage y be held in firm contact with the rail by means such as compressed air cylinders l1 and pistons 18 connected to the carriage, and may be raised, when testing is not desired, by releasing the fluid pressure and permitting springs (not 20 shown) and cables l9 to retract the said carriage. The electromagnetic field set up around the rail between the front and rear current brushes may be explored by flux responsive means mounted within a housing 39 and maintained at a constant as distance above the rail, as by skids 3| engaging the rail surface. The housing may be. mounted for movement independent of the current brush carriage so as to permit it to align itself with irregularities in the rail contour by mounting the so same on the current brush carriage by yielding or resilient means 33.

The flux responsive means may take the form of induction coils and in the presentinstance said coils may be positioned with their plane sub- 35 stantially parallel to the surface of the railhead and having, the ends of the cross-members 36 maintained at different temperatures by heating one end and cooling the other. This sets up a differential E. M. F. in the cross-members which is a function of the flux, so that as the flux varies, the E. M. F. generated therein varies, and the E. M. F.s may be caused to operate suitable indicators such as pen P on chart C after beingampii- 'fied by any suitable thermionic amplifier A to energize an output relay 3! which acts upon armature 38 connected to the pen.

A deficiency in the operation of this system is disclosed in the diagram of Fig. 3. If the coil is positioned so as to extend over a substantial portion of the railhead, and an internal fissure F within the rail is symmetrically positioned with and. a decrease in fiux at the center as', and that u the totalincrease is equal to the total decrease. In other words, the total flux afiecting the said coil remains the same as when there is no fissure of the Patent No. 1,963,931, I have a plurality of banks of coils positioned in a predetermined manner designed especially so that no matter where a fissure is positioned, at least one and perhaps more of said coils will experience a total increase or total decrease in the flux aifecting the same, to give an indication of flaw. At the same time, the arrangement is such as to permit the use of a single heater and a single cooler for all of said coils.

Referring to Figs. 4 and 5, it will be seen that I have shown a nest of coils 40, 4|, 42 housed one within the other. The sides 43, 44, 45 of the respective banks of coils are positioned closely adjacent to one another near one side of the railhead. This permits a single heater element 49 to heat all of said coils atone side thereof. The opposite side of each of said coils extends toward the other side of the railhead. but to difierent degrees. Thus, the sides 46, 41, and 48 are positioned progressively further from the sides 43, 44, 45 at progressively increasing distances toward the other side of the railhead. It will now be seen that each of the coils 40, 4| and 42 coacts with a diiferent sized portion of the railhead. If a fissure were so positioned with respect to coil 40, for instance, that the increase and decrease of flux aifecting said coil were equal and balanced each other, it is evident that such could not be the effect of the same fissure on coils 4| and 42 because said coils are so positioned asto be affected by more of one type of flux (increase or decrease) than by the other. Therefore, it is apparent that with the positioning of coils as described, it is impossible for any fissure to aifect all of said coils in such manner that the increase in fiux nullifies the decrease in flux, and therefore it is impossible for all of said coils to fail to detect any given fissure, but on the contrary at least one and perhaps several of said coils will respond to every fissure. A cooling element 50 can operate to cool all of the sides 46, "and 48 simultaneously.

In accordance with the provisions of the patent statutes. I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention. what I claim and desire to secure by Letters Patent is:

1. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector responsive to variations of flux in said field, said detector comprising a plurality of coils positioned one within the 1 other, said coils being of such size and so positioned as to cooperate with different portions of the railhead, and means for maintaining the portions of said coils at one side of the rail at a dif-.

ferent temperature from the portions of said coils at the other side of the rail.

2. In a rail flaw detector mechanism having means for establishing a magnetic field surround- I ing the rail and a detector responsive to variations of flux in said field, said detector comprising a plurality of coils positioned one within the other unsymmetrically with respect to the longitudinal axis of the rail, and means for maintaining the portions of said coils at one side of the rail at a difierent temperature from the portions of said coils at the other side of the rail.

3. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector responsive to variations of flux in said field, said detector comprising a plurality of coils positioned one within the other, said coils being of such size and so positioned unsymmetrically with respect to the railhead as to cooperate with difierent portions of the railhead, and means for maintaining the portions of said coils at one side of the rail at a different temperature from the portions of said coils at the other side of the rail.

4. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and adetector responsive to variations of flux in said field, said detector comprising a plurality of coils positioned one within the other unsymmetrically with respect to the longitudinal axis of the rail, a single heating means cooperating with the portions of said coils at one side of the rail and a single cooling means cooperating with the portions of said coils at the other side of the rail.

5. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector responsive to variations of fiux in said field, said detector comprising a plurality of coils positioned unsymmetrically'with respect to the railhead one within the other, said coils being of such size and so positioned as to cooperate with difierent portions of the railhead, a single heating means cooperating with the portions of said coils at one side of the rail and a single cooling means cooperating with the portions of said coils at the other side of the rail.

6. In a' rail fiaw detector mechanism having means for establishing a. magnetic field surrounding the rail and a detector responsive to varia-' tions of flux in said field aid detectorcomprising a plurality of coilsp tioned one within the other, said coils at one side of the railhead being positioned more closely adjacent each other than said coils at the other side thereof, and means for maintaining the portions of said coils at one side of the rail at a diflferent temperature from the portions of said coils at the other side of the rail.

7. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector responsive to variations of flux in said field, said detector comprising a plurality of substantially rectangular coils positioned one within the other, each coil having two sides substantially parallel to the longitudinal axis of the rail and two sides transverse thereof, said coils being of such size and so positioned unsymmetrically with respect to the railhead as to cooperate with difierent portions of the railhead.

8. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector .responsive to variations of flux in said field, said detector comprising a plurality of substantially rectangular coils positioned one within the other, each coil having two sides substantially parallel to the longitudinal axis of the rail and two sides transverse thereof, said coils being of such size' and so positioned unsymmetrically with respect to the railhead as to cooperate with different portions of the railhead, and means for maintaining the longitudinal portions of said coils at one side of the rail at a different temperature from the longitudinal portions at the other side of the rail.

9. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector responsive to variations of flux in said field, said detector comprising a plurality of substantially rectangular coils positioned one within the other, each coil having two sides substantially parallel to the longitudinal axis of the rail and two sides transverse thereof, the longitudinal portions of said coils at one side of the railhead being positioned more closely adjacent each other than the longitudinal portions of said coils at the other side thereof, and means for maintaining the portions of said coils at one side of the rail at a different temperature from the portions of said coils at the other side of the rail.

10. In a rail flaw detector mechanism having means for establishing a magnetic field surrounding the rail and a detector responsive to variations of flux in said field, said detector comprising a plurality of substantially rectangular coils positioned one within the other, each coil having two sides substantially parallel to the longitudinal axis of the rail and two sides trans verse thereof, the longitudinal portions of said coils at one side of the railhead being positioned more closely adjacent each other than the iongitudinal portions of saidcoils atthe other side thereof, a single heating means for the longitudinal portions of said coils at one side of the railhead and a single cooling means for the longitudinal'portions at the other side of the railhead,

HARCOURT C. DRAKE. 

